Is there is current limit on the NI USB module 9263 Analog Voltage Out (+/-10V)?

[CowdogHank87]

Is there is current limit on the NI USB module 9263 Analog Voltage Out (+/-10V)? I'm trying to run a current controlled servovalve, but cannot get the required current. The servovalved has a parallel internal resistance of 80 ohms, and requires 20 mA to function fully. Ohms law: (.02 A) * ((80*80)/(80+80) ohms = 4.5 V. Yet, at the required voltage, the servovalves don't move. Aside from hardware error (pursuing this by other means) what could be the issue?

[RavensFan · Accepted solution]

Did you check the manual?

Page 12 says 1 mA.

For Servo valves, you really require some sort of amplifier.  See if the manufacturer provides any driver electronics for it.

[CowdogHank87]

Thanks, I forgot to check the manual...

[BrainDrain]

Just another remark ... wich goes towards NI...

On the very top  of the online description of the NI 9263 module (http://sine.ni.com/ds/app/doc/p/id/ds-59/lang) it is stated:

"±10 V and 0 to 20 mA analog output ranges, 16-bit resolution, 100 kS/s simultaneous update rate" . So how can this be stated if later on the max current drive is given as ±1mA?

Do I miss something here?

I ordered  the module because my application needed 14mA @ 5V (strain gauge with an 350Ohm input resistance). Therefore the 20mA stated above should have been sufficient... Unfortunately, nothing works... wich is not a surprise looking at the max. current drive of 1mA/channel!

Best regards,

Luke

[RavensFan]

The description at the top is providing the overview of all modules within that family.

You need to pay attention to the specific details for each model in the table lower on the page.

If you have a strain gage you are trying to read, then you should be selecting a strain gage input module, not an analog output module.  The strain gage modules will provide the excitation for the strain gage bridge as well as read the signal and provide the mV/V correlation of input to output.

[BrainDrain]

Thank you for the reply.  On the German website allmost all of the technical specifications are given except the max. output current. For full specification you are redirceted to this site (see below). If the haeding is: 4-Channel, 100 kS/s, 16-Bit, ±10 V, Analog Output Module NI 9263, I would assume that the next sentences do refer to module not to the module familiy. And because  I found the missing bit of information within the next lines, there was no need to read further...   

At the end, it was not a big deal, because the problem can be easily solved with a simple transistor circuit. However, it was just a bit  annoying, because the way the information is presented is misleading and that is the point I wanted to make... 

Best wishes,

Luke

4-Channel, 100 kS/s, 16-Bit, ±10 V, Analog Output Module

NI 9263

±10 V and 0 to 20 mA analog output ranges, 16-bit resolution, 100 kS/s simultaneous update rate 4 channels per module Isolation up to 2,300 Vrms (withstand), up to 250 Vrms (continuous) Per-channel digital-to-analog converter (DAC) for simultaneous analog output	±30 V overvoltage protection and short-circuit protection for direct connection to actuators and industrial devices Excellent relative accuracy optimized for single-point control applications NIST-traceable calibration certificate

[BrainDrain]

... regarding the strane gage ... I needed specifically an analog output module in order to drive the strange gage. The output signal is amplified and detected by a n NI 9215.

Best wishes,

Luke